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Temporal Changes in Invertebrate Communities Water column-invertebrates Sample period mean densities for water column invertebrates for each community are presented in Figure 29. The bulrush- --.community mean on 30 July had the greatest density for all communities over the season. with 124 organisms L-1. On the subsequent sample period however the density of invertebrates dropped to the lowest level of the season at 5 organisms L'i. The open water community had its lowest densities on the-first samgie date at 1.6 organisms L'1, but on the next-sample period. .reached a maximum for the season with 80 L'1. A general decline- in water column .invertebrates-was seen up to the .last-sample date where a slight increase was seen. Tn the flooded willow community densities were generally below that seen in the bulrush- - and open water communities except on the 13 August sample date -when this community :had the greatest density of invertebrates at 56 L'1. An earlier and much less pronounced peak was seen on the second sample period in this community.' The backwater community water column invertebrates were at much lower densities. than that seen in the off channel wetlands. The maximum mean density for this community was 2.9 organisms L'1 on the 13 August, No-water column invertebrates were found in samples on the fourth and last sample periods. Water column invertebrates were always found in the river community over the sample season.. These. densities were very low however with a maximum occurring on the 30 July with 0.3 organisms L'1. Benthic Invertebrates In the bulrush community benthic invertebrates. were at a maximum. on-the 13 August with a density of 159 L'1 (Figure 30). Up o.this sample period densities were generally well below-this level and again fell off to low levels on the. subsequent sample date. No benthic invertebrates were found in samples on the first sample date in the bulrush community. The open water .community had maximum densities on-the first sample period with -188 organisms L-1. This.-was-the greatest density seen for benthic invertebrates over the sample season for all communities. .Densities did decline to zero on the fourth and fifth sample periods with a modest increase seen on the-last sample period to a density of 43 L'1. No benthic .invertebrates were found in samples-from-the flooded willow-community-over season. In the backwater community densities of benthic invertebrates-were only ,seen on-the forth and fifth sample periods. These densities-were at lower levels compared to those seen at ,other communities over- -- the season. River benthos.were-not frequently .found in samples